Innovative, efficient processes are developed for the recovery of rare-earth elements (REEs) and other critical metals (PGMs, Ge, In, Sb, Ga, Co, Ta) from end-of-life consumer goods, industrial process residues and low-grade ores. A combined use is made of pyro-, hydro-, solvo-, iono-, electro- and biometallurgical methods. The recovery of the critical metals is part of larger flow sheets, which target zero-waste valorisation of the metal-contaiming residues.
- Design of extractants and adsorbents for critical metal recovery: New extractants and adsorbents are designed, synthesised and characterised. Special attention is paid to new ionic liquid extractants and to adsorbents derived from biopolymers (chitosan and alginate). Also traditional extractants are prepared in high purity for fundamental studies.
- Solvometallurgical leaching and preconcentration of critical metals: In solvometallurgical processes, the aqueous phase of hydrometallurgical processes is partly or completely replaced by an organic solvent. One approach is “solvent leaching” in which the leaching is performed with a complexing agent (acting as an extractant) in an organic solvent. Lixiviants are often more reactive in organic solvents than in water. A second solvometallurgical method is “slurry solvent extraction”. Here, the finely crushed ore is wetted by a small volume of acid solution, and this slurry is contacted with a water-immiscible organic phase, containing an extractant. This approach is similar to conventional solvent extraction, but the volume of the aqueous phase is largely reduced.
- Solvent extraction for separation and purification of critical metals: Undiluted ionic liquids are used in solvent extraction processes for the separation of mixtures of rare earths and for the purification of other critical metals. Undiluted ionic liquids offer in solvent extraction the advantage of a very high extractant concentration, allowing for high metal loadings in the organic phase. Because other extraction mechanisms are operational for solvent extraction with ionic liquids than for molecular solvents, more selective extraction processes can be designed with ionic liquids.
- Critical metal recovery from dilute aqueous waste streams: Metal ions are recovered from dilute aqueous waste streams and leachates by means of highly selective adsorbents. Two types of adsorbents are being considered: (1) adsorbents made by functionalisation of biopolymers such as chitosan or alginate, and (2) supported ionic liquid phases (SILPs). In SILPS an ionic liquid is immobilised on a solid support. SILP technology is very flexible, because both the type of ionic liquid and the solid support can be optimised independently. By the use of functionalised ionic liquids, very selective adsorbents can be obtained.
- Alternative energy forms (magnetic, microwave, ultrasound) for process intensification and enhanced metal recovery: Leaching of metals is accelerated by microwave irradiation or ultrasound, but it is also possible to get more selective leaching by these methods. Separation of paramagnetic from diamagnetic metal ions by strong magnetic fields is an innovative new approach to the separation of mixtures of metal ions.
- Quantitative characterisation and distribution analysis of critical metals in primary raw materials and residues: Procedures for the quantitative analysis of platinum-group metals, rare earths and other critical metals in a variety of minerals and residues by field emission gun electron microprobe (FEG-EPMA) are being developed.
Presently, about 20 students and postdocs are working at KU Leuven on recovery of critical metals. The leading members are.
Prof. Koen Binnemans (RL Leader) is a world-leading expert in the chemistry of REEs and the environmentally-friendly use of ILs in solvent extraction and critical metal recovery. Author of more than 200 papers on REEs (320 papers in total) with a h-index of 48 (54 according to Google Scholar) and over 10000 citations. General coordinator of EU FP7 MC-ITN EREAN and H2020 MSCA-ETN REDMUD, and Steering Committee Member of ERECON (DG Enterprise and Industry). Vice-chair of the European Rare-Earth and Actinide Society (ERES).
Prof. Jan Fransaer is a full professor of chemistry (Department of Materials Engineering). His research group has a tradition in experimental & computational electrochemistry. More than 100 peer reviewed publications and 11 patents in this field. He was involved in 7 EU projects (2 as coordinator) on electrodeposition. The group made significant contributions to the practical and theoretical understanding of the electrodeposition of particles together with metals, and was one of the first to study this process using non-aqueous electrolytes.
Dr. Peter Tom Jones is a Senior Industrial Research Fund Research Manager. He is Valorisation Officer of several large-scale projects and networks at the level of KU Leuven, Flanders and the EU. He is also actively involved in the EIT Raw Materials. He chairs the EU-wide EURELCO Consortium. He takes care of the valorisation tasks within the research line and spearheads the contacts with major critical metal industrial players such as Solvay-Rhodia, Umicore, Molycorp Silmet, Toyota, Veolia etc.
Prof. Tom Van Gerven has a background in chemical engineering and is a specialist in process intensification using localised energy and alternative energy forms (ultrasound, light, microwaves etc.). Prof. Van Gerven’s role in RARE³ is the application of process intensification techniques to the leaching of low grade ores and industrial process residues and to the solvent extraction. This includes ultrasound- and microwave-assisted leaching, light-assisted separations and the use of microflow reactors for solvent extraction.
Prof. Philippe Muchez is head of the Ore Geology and Geofluids Research Group. He carried out post-doctoral research at the University of Liverpool and at the Vrije Universiteit Amsterdam. Laureate of the Royal Academies for Science and the Arts of Belgium. Member of Royal Academy for Overseas Sciences. His research focusses on the migration of fluids in sedimentary basins and ore-forming processes, i.e. Pb-Zn deposits in Europe, and Nb-Ta-Sn-W-Au deposits in Central Africa.